SQL Update with Subquery as Data source doesn´t work (Postgresql) - sql

Question

i have the following SQL DML Update command, but the syntax isn´t correct and the command doesn´t work:
UPDATE hmsg_vehicle_category
SET hmsg_vehicle_category.hmsg_id, hmsg_vehicle_category.vehiclecategories_inputname
SELECT l_p.hmsg_id, tmp_p_vc.inputname
FROM hmsg_him_product AS l_p INNER JOIN ( SELECT p.id, vc.inputname
FROM him_product p INNER JOIN vehicle_category vc
ON p.id = vc.product
ORDER BY p.id, vc.inputname DESC ) AS tmp_p_vc
ON l_p.products_id = tmp_p_vc.id
WHERE l_p.hmsg_id = 171;
How can i execute this SQL command? Where is the mistake in the snytax?
Thanks for help !
Greetz
Marwief

Answer 1

Something like:
update hmsg_vehicle_category set
hmsg_id = l_p.hmsg_id,
vehiclecategories_inputname = tmp_p_vc.inputname
from hmsg_him_product as l_p
inner join him_product as p on p.id = l_p.products_id
inner join vehicle_category as vc on vc.product = p.id
where l_p.hmsg_id = 171
Be warned, this one will update all records in hmsg_vehicle_category table. May be you want to add this into where clause:
update hmsg_vehicle_category as hvc set
vehiclecategories_inputname = tmp_p_vc.inputname
from hmsg_him_product as l_p
inner join him_product as p on p.id = l_p.products_id
inner join vehicle_category as vc on vc.product = p.id
where
l_p.hmsg_id = 171 and hvc.hmsg_id = 171
But I cannot advice something more specific at the moment, because it's unclear from your question.